Unsaturated fatty compounds with improved low-temperature behavior

ABSTRACT

A process for producing unsaturated fatty compounds having improved low-temperature properties by 
     a) splitting lauric oils into fatty acids and glycerol, 
     b) subjecting the fatty acids to fractional crystallization to obtain a fraction of unsaturated fatty acids, and 
     c) hydrogenating the unsaturated fatty acids, optionally after converting the unsaturated fatty acids into their lower alkyl esters, to form unsaturated fatty alcohols having an iodine value of from about 85 to about 100.

This application is a 371 of PCT/EP95/02646 filed Jul. 7, 1995.

FIELD OF THE INVENTION

This invention relates to unsaturated fatty compounds with improvedlow-temperature behavior which are obtained by splitting selectedvegetable oils into fatty acids and glycerol, subjecting the resultingsplit fatty acids to fractional crystallization and hydrogenating theaccumulating fraction of substantially unsaturated fatty acids,optionally after conversion into the methyl esters, with the doublebonds intact to form the corresponding fatty alcohols. The inventionalso extends to derivatives of the unsaturated fatty alcohols, toprocesses for their production and to their use for the production ofsurface-active formulations. Finally, the invention relates to the useof selected vegetable oils for the production of unsaturated fattyalcohols.

DISCUSSION OF RELATED ART

Fatty compounds, more particularly unsaturated fatty alcohols, areimportant intermediates for a large number of products of the chemicalindustry, for example for the production of surfactants and cosmeticproducts. An overview of this subject was published, for example, by U.Ploog et al. in Seifen-Ole-Fette-Wachse 109, 225 (1983).

Unsaturated fatty alcohols cannot be produced on the basis ofpetrochemical raw materials and processes. Instead, they are producedfrom more or less unsaturated fatty acids or methyl esters thereof basedon renewable raw materials which are hydrogenated with the double bondsintact, for example in the presence of chromium- and/or zinc-containingmixed oxide catalysts cf. Ullmann's Enzyklopaedie der technischenChemie, Verlag Chemie, Weinheim, 4th Edition, Vol. 11, pages 436 etseq.!.

Basically, unsaturated fatty alcohols can be produced in three ways:

1. Fats and oils are subjected to pressure hydrolysis with water. Afterremoval of the water-containing glycerol, split fatty acids representingmixtures of saturated and unsaturated fatty acids are obtained. Sincethe co-hydrogenation of these acids is unable to influence the ratio ofsaturated and unsaturated components, it is only possible in this way toobtain fatty alcohols with a low iodine value below 85 which are lesspreferred.

2. Saturated and unsaturated C_(16/18) fatty acids cannot be separatedby distillation. In contrast to (1), however, the split fatty acids canbe converted by so-called rolling-up into a predominantly saturatedfatty acid cut and a predominantly unsaturated fatty acid cut.Hydrogenation of the unsaturated fatty acid cut gives technical oleylalcohols with an iodine value in the range from about 85 to 100.

3. In addition, highly unsaturated vegetable oils can be subjected totransesterification in which methyl esters with a comparatively lowpercentage content of saturated homologs are obtained. In this case,rolling-up is neither possible nor necessary because the hydrogenationdirectly yields highly unsaturated fatty alcohols (I.V.>100).

The three processes mentioned have long been commercially used for theproduction of unsaturated fatty alcohols. It is logical to use startingmaterials already having a high iodine value for the production ofunsaturated fatty alcohols.

Examples of suitable starting products for process 1 are fats and oilswith an iodine value of 40 to 70, such as for example beef tallow, lard,palm oil or palm stearin. Suitable starting materials for the productionof highly unsaturated fatty alcohols by process 3 are, for example,rapeseed oil, olive oil, sunflower oil, linseed oil or peanut oil.

Starting materials such as coconut oil or palm kernel oil, for example,have not hitherto been considered for the production of unsaturatedfatty alcohols with iodine values in the range from 90 to 100 becausethey contain too small a percentage of unsaturated species.

Unfortunately, the unsaturated commercial fatty alcohols obtainable bythe processes described above have various disadvantages. Products withan iodine value below 80 are wax-like. Apart from their unfavorablesolidification point, they do of course only have some of the advantagesassociated with the unsaturated structure. Highly unsaturated fattyalcohols (iodine value>100) contain a significant percentage ofpolyunsaturated homologs and, for this reason, are not stable toautoxidation. Although the products are liquid, they are difficult toincorporate in creamy or paste-like formulations. From the performancepoint of view, therefore, unsaturated fatty alcohols with iodine valuesin the range from 85 to 100 are the most suitable. However, they areoften unsatisfactory both in regard to their color and in regard totheir odor quality and also have an unfavorably high solidificationpoint for many applications.

Accordingly, the problem addressed by the present invention was toprovide unsaturated fatty alcohols with an iodine value in the rangefrom 85 to 100 based on vegetable raw materials--and correspondingderivatives--which would be distinguished in particular by improvedlow-temperature behavior and color and odor quality.

DESCRIPTION OF THE INVENTION

The present invention relates to unsaturated fatty compounds withimproved low-temperature behavior obtainable by

(a) splitting lauric oils into fatty acids and glycerol,

(b) subjecting the resulting split fatty acids to fractionalcrystallization and

(c) hydrogenating the fraction of predominantly unsaturated fatty acids,optionally after conversion into the lower alkyl esters, to form thecorresponding unsaturated fatty alcohols with iodine values in the rangefrom 85 to 100 and preferably in the range from 90 to 95.

It has surprisingly been found that, by using selected vegetable oilswith a low iodine value range and by purifying the unsaturated fattyacids produced as intermediate stages on this basis in the hydrogenationstep, it is possible for the first time to obtain unsaturated vegetablefatty alcohols which not only have extremely good color and odorproperties, they are also distinguished as required by particularlyadvantageous low-temperature behavior. The use of the raw materialsmentioned with their low iodine values in a process known per se, whichfor economic reasons has hitherto only been known for its application toraw materials with distinctly higher iodine values, appears to be newand inventive in view of the surprising effects observed.

Other advantageous embodiments of the invention are derivatives whichalso show favorable low-temperature behavior and improved color and odorproperties and which are obtained by subjecting the unsaturated fattyalcohols mentioned at the beginning in known manner to

alkoxylation;

alkoxylation, sulfation and neutralization;

sulfation and neutralization; or

esterification with aliphatic carboxylic acids containing 1 to 22 carbonatoms and 0 and/or 1 to 3 double bonds.

Production process

The present invention also relates to a process for the production ofunsaturated fatty compounds with improved low-temperature behavior, inwhich

(a) lauric oils are split into fatty acids and glycerol,

(b) the resulting split fatty acids are subjected to fractionalcrystallization and

(c) the fraction of predominantly unsaturated fatty acids ishydrogenated, optionally after conversion into the lower alkyl esters,to form the corresponding unsaturated fatty alcohols with iodine valuesin the range from 85 to 100 and preferably in the range from 90 to 95.

Lauric oils

Lauric oils in the context of the invention are understood to be palmkernel oil, coconut oil and babassu oil and mixtures thereof in whichthe C chain distribution is centered on the C₁₂ to C₁₄ range. Typicalcompositions are shown in Table 1.

                  TABLE 1    ______________________________________    Typical Composition of Palm Kernel Oil and Coconut Oil                   Palm Kernel Oil                               Coconut Oil    Fatty Acid Component                   % By Weight % By Weight    ______________________________________    Caproic acid   0-1         0-1    Caprylic acid   3-10       6-9    Capric acid     3-14        6-10    Lauric acid    37-52       44-51    Myristic acid   7-17       13-18    Palmitic acid  2-9          8-10    Stearic acid   1-3         1-3    Oleic acid     11-23       6-3    Linoleic acid  1-3         0-3    Saponification value                   245-255     250-264    Iodine value   14-23       8-11    Melting point (° C.)                   26--26      23-26    ______________________________________

In the context of the invention, other fats and oils or mixtures thereofwhich also have iodine values of 5 to 25, a content of C₁₂₋₁₄ fattyacids of 30 to 55% by weight and a total linoleic (linolenic) acidcontent of <5% by weight, are regarded as direct equivalents which areencompassed by the present teaching.

It is preferred to use palm kernel oil from which a technical oleylalcohol with an iodine value of 94, a solidification point of 7° C., acolor of 10 Hazen and a composition of 5% by weight C₁₆ and 95% byweight C₁₈ can be produced by the process according to the invention.

Splitting

In the context of the invention, splitting is understood to be thesaponification or hydrolysis of glycerol fatty acid (partial) estersinto glycerol and fatty acids. The process goes back to E. Twitchellwho, in 1898, developed a normal-pressure process for the splitting oftriglycerides in which the hydrolysis was carried out in the presence ofsulfuric acid and a mixture of naphthalene and oleic acid (Twitchellreagent). Since the development of suitable stainless steels in thethirties, the pressure hydrolysis of fats known since 1854 has also beencarried out industrially with steam cf. Fat Sci. Technol., 89, 297(1987)!. The latter process--besides the EMERSOL process--is preferredfor the purposes of the invention.

Fractional crystallization and rolling-up

The separation of saturated and unsaturated C_(16/18) fatty acids iscarried out as fractional crystallization. It is preferably based onso-called rolling-up. Rolling-up is understood to be the separation ofsaturated and unsaturated fatty acids generally containing 12 to 18 andpreferably 16 to 18 carbon atoms which are impossible or very difficultto separate by distillation on account of their very similar boilingpoints. A review of this subject was published by K. Schmid in Fat Sci.Technol., 89, 237 (1987).

The process of rolling-up was developed at the beginning of the sixtiesfor the separation of tallow fatty acid into a C_(16/18)palmitic/stearic acid cut ("stearin") and an oleic acid fraction("olein"), but is also applicable to split fatty acids with a broader Cchain distribution. In the case of tallow fatty acid, the process iscarried out by initially cooling the technical fatty acid mixture to lowtemperatures of around 5° C., the palmitic/stearic acid undergoingcrystallization in the liquid oleic acid to form a dispersion. Althoughphysical separation could be carried out here, it has been found that,in the case of filtration for example, excessively large amounts ofoleic acid adhere to the palmitic/stearic acid crystals. In order to"wash off" the oleic acid from the crystals, an aqueous wetting agentsolution, for example an aqueous alkyl sulfate is added to thedispersion. Subsequent centrifugation of this emulsion/dispersionresults in breaking of the emulsion into an oleic acid phase and awater/saturated fatty acid dispersion which can be separated in aseparator. The palmitic/stearic acid-water dispersion is then heated toaround 50 to 80° C. and the molten palmitic/stearic acid is separatedfrom the aqueous wetting agent solution which is returned to theprocess.

Hydrogenation

The reduction of esters with metallic sodium in the presence of analcohol was discovered by Bouveault and Blanc in 1903. Nowadays,however, the production of fatty alcohols on an industrial scale iscarried out almost exclusively by high-pressure hydrogenation ofdistilled or fractionated methyl ester or fatty acid cuts in one or morefixed-bed or shaft reactors arranged in tandem at temperatures of 200 to250° C. and under a hydrogen pressure of 200 to 300 bar. To this end,the fatty acid or methyl ester is continuously forced into theinstallation against the hydrogen pressure, heated to the reactiontemperature and introduced at the head of the reactor. Adkins catalystbeds based on Cu/Cr/Zn and/or Cu/Cr/Cd mixed oxides are normally usedfor the production of unsaturated fatty alcohols. In this case, thecarboxyl(ate) group is selectively hydrogenated with the double bondspresent in the fatty residue intact.

In addition to the fixed-bed procedure, the hydrogenation may also becarried out in the trickle phase. In this variant, too, fatty acid orester and hydrogen flow through the reactor from above at a temperatureof 200 to 300° C. and under a pressure of 250 to 300 bar. In this case,however, the quantities of recycle gas and the molar excess of hydrogenare considerably smaller which is reflected in smaller plant dimensions.Silica gel supported catalysts containing 20 to 40% by weight of thecopper chromites mentioned at the beginning are used as catalysts.Although these catalysts have high mechanical stability, they are moresusceptible to poisoning than solid catalysts on account of their lowcontent of active substance and, accordingly, have shorter lives.

The resulting fatty alcohols are then preferably purified bydistillation in known manner with removal of first runnings (around 5%by weight).

If desired, purification may be followed by a second fractionalcrystallization ("winterizing").

Mixtures

In another advantageous embodiment of the invention, the new unsaturatedfatty alcohols based on palm kernel oil and/or coconut oil may be mixedwith conventional saturated and/or unsaturated fatty alcohols containing6 to 22 and preferably 16 to 18 carbon atoms. The advantage is that themixtures also show improved performance properties.

For example, a mixture of 60 to 65% by weight of a technical oleylalcohol according to the invention based on palm kernel oil and 35 to40% by weight of a conventional oleyl alcohol (HD Ocenol® 60/65, HenkelKGaA) has a solidification point below 20° C. By contrast, thesolidification point of an oleyl alcohol of comparable composition (HDOcenol® 70/75, Henkel KGAA) based on beef tallow is 22° C.

Derivatization

As mentioned at the beginning, the present invention also includes theobservation that the excellent properties of the unsaturated fattyalcohols initially produced remain intact even after derivatization.This includes:

Alkoxylation. Alkoxylates of the unsaturated fatty alcohols are obtainedin known manner by addition of ethylene and/or propylene oxide in thepresence of basic catalysts, for example sodium methylate or calcinedhydrotalcite, and may have both a conventional homolog distribution anda narrow homolog distribution. The alkoxylates are suitable, forexample, as raw materials for detergents, as emulsifiers in the textilesfield, in drilling and cutting oils and in cosmetic formulations.

Alkoxylation/sulfation. Ether sulfates of the unsaturated fatty alcoholsare obtained in known manner by alkoxylation, subsequent sulfation withgaseous sulfur trioxide or chlorosulfonic acid and, finally,neutralization with bases. The products are suitable as raw materialsfor detergents.

Sulfation. Fatty alcohol sulfates based on the unsaturated alcohols areobtained in known manner by sulfation with gaseous sulfur trioxide orchlorosulfonic acid and subsequent neutralization with bases. Theproducts are also suitable as detergents for raw materials and astextile auxiliaries.

Esterification. Esters of the unsaturated fatty alcohols are obtained inknown manner by catalytic reaction with aliphatic carboxylic acidscontaining 1 to 22, preferably 6 to 22 and more preferably 12 to 18carbon atoms and 0 and/or 1 to 3 double bonds. Typical examples arereactions of a technical oleyl alcohol according to the invention(iodine value 95) with acetic acid, C₆₋₁₀ head-fractionated fatty acid,lauric acid, palmitic acid, stearic acid, oleic acid, C_(12/14)cocofatty acid, C_(12/18) cocofatty acid or C_(16/18) tallow fatty acid.The esterification is preferably carried out with oleic acid to form anoleyl oleate. The products are suitable for example, as oils for theproduction of cosmetic formulations.

Other derivatizations which may also be considered include amidation,phosphatization, the formation of adducts with maleic anhydride andepoxidation, preferably after conversion of the oleyl alcohols into themethyl esters.

Commercial Applications

The unsaturated fatty compounds according to the invention aredistinguished from known products by an improved odor, an improved colorand, in particular, by more advantageous low-temperature behavior.

The present invention also relates to their use for the production ofsurface-active formulations such as, for example, superfatting agents orsolvents for active substances, cremes, emollients and lotions,lubricants for the machining of metals and antifoam agents in dispersionpaints, in which they may be present in quantities of 1 to 75% by weightand preferably 5 to 50% by weight, based on the particular product.

Finally, the present invention also relates to the use of lauric oilsfor the production of unsaturated fatty alcohols with iodine values of85 to 100 and preferably 90 to 95 by splitting, fractionalcrystallization and hydrogenation.

EXAMPLES General Production Procedures

Method 1. The starting materials were subjected to pressure hydrolysisand the glycerol/water mixture was removed. After conversion into themethyl ester, the resulting split fatty acid mixture was hydrogenatedwithout further purification with the double bonds intact. The productwas then purified by distillation.

Method 2. The starting materials were subjected to pressure hydrolysisand the glycerol/water mixture was removed. The resulting split fattyacid mixture was separated by rolling-up into a stearin fraction and anolein fraction. The olein, which contained around 80% by weight of oleicacid, was esterified with methanol and then hydrogenated with the doublebonds intact. The product was then purified by distillation.

Method 3. The starting materials were transesterified with methanol andfreed from glycerol and unreacted alcohol. The resulting methyl estermixture was hydrogenated without further purification with the doublebonds intact. The product was then purified by distillation.

The composition of the raw materials used is shown in Table 2(percentages as % by weight). Table 3 shows the performance data of theresulting unsaturated fatty alcohols.

                  TABLE 2    ______________________________________    Raw Materials Used                  PK    CC      BT  PM     PS  OL    Fatty Acid Component                  %     %       %   %      %   %    ______________________________________    Caproic acid  1     1       0   0      0   0    Caprylic acid 4     8       0   0      0   0    Capric acid   5     7       0   0      0   0    Lauric acid   50    48      0   0      0   0    Myristic acid 15    17      3   2      4   10    Palmitic acid 7     9       27  42     72  3    Stearic acid  2     2       22  5      10  0    Oleic acid    15    7       43  41     11  80    Linoleic acid 1     1       5   10     3   7    Iodine value  19    9       44  50     15  82    ______________________________________     Legend:     PK = Palm kernel oil     PM = Palm oil     CC = Coconut oil     PS = Palm stearin     BT = Beef tallow     OL = Olive oil

                  TABLE 3    ______________________________________    Characteristic Data of the Products               Unsaturated Fatty Alcohol                                   SP    Color    Ex.  Raw Material                     I.V.    Method                                   ° C.                                         Hazen Odor    ______________________________________    1    Palm kernel oil                     94      2     7.0   10    +++    2    Coconut oil 91      2     8.5   15    ++    C1   Palm kernel oil                     35      1     30.5  20    +    C2   Coconut oil 35      1     32.0  25    +    C3   Beef tallow 94      2     14.5  85    -    C4   Palm oil    94      2     15.5  90    -    C5   Palm stearin                     94      2     17.0  90    -    C6   Olive oil   112     2     7.0   25    +    C7   Olive oil   108     3     7.0   120   +    ______________________________________     Legend:     I.V. = Iodine value     SP = Solidification point     Odor = +++ = Odorless     ++ = Odor hardly noticeable     + = Odor noticeable     - = Odor distinctly noticeable

Example 3

The unsaturated oleyl alcohol of Example 1 was esterified with palmkernel oil fatty acid (Edenor® PK 1805, Henkel KGaA). The resultingester had the following characteristic data:

    ______________________________________    Hydroxyl value   209    Iodine value     94    Saponification value                     0.3    Solidification point                     7.2    Color value (APHA)                     10    ______________________________________

What is claimed is:
 1. Unsaturated fatty alcohols having an iodine valueof from about 85 to about 100 and improved low-temperature propertiesprepared by;a) splitting lauric oils having an iodine value of 5 to 25into fatty acids and glycerol, b) subjecting said fatty acids tofractional crystallization to obtain a fraction of unsaturated fattyacids, and c) hydrogenating said unsaturated fatty acids, optionallyafter converting said unsaturated fatty acids into their lower alkylesters.
 2. Unsaturated fatty alcohols as in claim 1 wherein said lauricoils are selected from palm kernel oil and coconut oil.
 3. Unsaturatedfatty alcohols as in claim 1 wherein said lauric oils are subjected topressure hydrolysis with water.
 4. Unsaturated fatty alcohols as inclaim 1 wherein said fractional crystallization step is carried out byrolling-up.
 5. Unsaturated fatty alcohols as in claim 1 wherein saidunsaturated fatty alcohols are alkoxylated.
 6. Unsaturated fattyalcohols as in claim 1 wherein said unsaturated fatty alcohols aresubsequently alkoxylated, sulfated and neutralized.
 7. Unsaturated fattyalcohols as in claim 1 wherein said unsaturated fatty alcohols aresubsequently sulfated and neutralized.
 8. Unsaturated fatty alcohols asin claim 1 wherein said unsaturated fatty alcohols are subsequentlyesterified with aliphatic carboxylic acids containing 1 to 22 carbonatoms and 0 or 1 to 3 double bonds.
 9. Unsaturated fatty alcohols as inclaim 1 wherein said unsaturated fatty alcohols are mixed with othersaturated or unsaturated fatty alcohols containing 6 to 22 carbon atoms.10. The process of producing unsaturated fatty compounds having improvedlow-temperature properties comprising:a) splitting lauric oils having aniodine value of 5 to 25 into fatty acids and glycerol, b) subjectingsaid fatty acids to fractional crystallization to obtain a fraction ofunsaturated fatty acids, and c) hydrogenating said unsaturated fattyacids, optionally after converting said unsaturated fatty acids intotheir lower alkyl esters, to form unsaturated fatty alcohols having aniodine value of from about 85 to about
 100. 11. A process as in claim 10wherein said lauric oils are selected from palm kernel oil and coconutoil.
 12. A process as in claim 10 including subjecting said lauric oilsto pressure hydrolysis with water.
 13. A process as in claim 10 whereinsaid functional crystallization step is carried out by rolling-up.
 14. Aprocess as in claim 10 including alkoxylating said unsaturated fattyalcohols.
 15. A process as in claim 10 including alkoxylating, sulfatingand neutralizing said unsaturated fatty alcohols.
 16. A process as inclaim 10 including sulfating and neutralizing said unsaturated fattyalcohols.
 17. A process as in claim 10 including esterifying saidunsaturated fatty alcohols with aliphatic carboxylic acids containing 1to 22 carbon atoms and 0 or 1 to 3 double bonds.
 18. A process as inclaim 10 including mixing said unsaturated fatty alcohols with othersaturated or unsaturated fatty alcohols containing 6 to 22 carbon atoms.